Weistec has released CNC ported heads for the Mercedes M156 6.2 liter V8 engine. Weistec claims this is the first head solution although we believe MHP had an option available first. Regardless, claim is a 40-50 horse gain on naturally aspirated motors and 70-80 on supercharged motors. No dynos released but flow charts are below.

I think you just have to be careful on what's being claimed. Not the first ported-heads solution, but the first CNC-ported-heads solution. Also, the vague, general claim that "Heads can add an extra 40-50 HP on naturally aspirated engines, and up to 70 HP on supercharged engines with stock cam shafts." makes me wonder if this has back-to-back dynos to support the marketing piece, or if these are just educated guesses at this point.

I dont see why 40-50 hp is an unreasonable gain on an NA motor. almost 400 cfm of flow intake is no joke. If the heads are smallish to begin with, then huge can gains can be realized and are definitely a legitimate claim IMO.

Also, the price seems very reasonable considering this is a MB AMG car and they are CNC'd. A fair price and great mod, I really want to see what these heads can do with an MHP tune and those aftermarket cams and headers. $#@! that would sound HEINOUS!!

I think you just have to be careful on what's being claimed. Not the first ported-heads solution, but the first CNC-ported-heads solution. Also, the vague, general claim that "Heads can add an extra 40-50 HP on naturally aspirated engines, and up to 70 HP on supercharged engines with stock cam shafts." makes me wonder if this has back-to-back dynos to support the marketing piece, or if these are just educated guesses at this point.

Interesting developments, nonetheless.

Oh I am, which is why I made sure to state there is no dyno to support it and that MHP already had heads available. These numbers should just be taken as unsupported claims as you stated. The new development needs to be reported though even if there isn't support for all the claims.

50HP is simply not possible, the castings are too good from the factory. However by looking at the pics evidently weistec didn't agree. Way too much material removed from the ports themselves, bye bye velocity. Also, where did the valve guides go? They're mowed down so far there is no valvetrain stability and the valves will beat the seats to death.

50HP is simply not possible, the castings are too good from the factory. However by looking at the pics evidently weistec didn't agree. Way too much material removed from the ports themselves, bye bye velocity. Also, where did the valve guides go? They're mowed down so far there is no valvetrain stability and the valves will beat the seats to death.

50HP is simply not possible, the castings are too good from the factory. However by looking at the pics evidently weistec didn't agree. Way too much material removed from the ports themselves, bye bye velocity. Also, where did the valve guides go? They're mowed down so far there is no valvetrain stability and the valves will beat the seats to death.

This why not just anyone should port a quality 4v head.

I can see 50 chp! with the proper intake manifold and TB set-up. I have always took down the guides a tad bit on ported heads and have had over 100k miles on a set that the guides where ground down.

I can see 50 chp! with the proper intake manifold and TB set-up. I have always took down the guides a tad bit on ported heads and have had over 100k miles on a set that the guides where ground down.

I didn't post those facts in the form of a question, you've never seen M156 heads in person, there isn't 50HP to gain anywhere. As for the valve guides, just because it "worked" on one motor doesn't mean it's good practice there's obviously a reason why. Do you know how much M156 valves weigh? All this needs to be taken into consideration and more and the facts aren't publicly available unless you've tested them yourself.

Ever seen a M156 intake manifold? You can't port it, it's half plastic half Mg and perfect in shape. What are you going to do about the stock dual 74mm TBs that are integrated into the bottom of the manifold?

It seems as though you are making blanket statements about motors in general, the shoe doesn't fit here.

I didn't post those facts in the form of a question, you've never seen M156 heads in person, there isn't 50HP to gain anywhere. As for the valve guides, just because it "worked" on one motor doesn't mean it's good practice there's obviously a reason why.

Ever seen a M156 intake manifold? You can't port it, it's half plastic half Mg and perfect in shape. What are you going to do about the stock dual 74mm TBs that are integrated into the bottom of the manifold?

It seems as though you are making blanket statements about motors in general, the shoe doesn't fit here.

Isnt the sls intake manifold better? I never mentioned porting the intake mani! I would just send the stocker to wilson and have them fab one up. So if there is not 50 crank hp to gain then there is no point in doing heads on a m156 period end of discussion. When I purchase a C63 it looks like it will get some exhaust and a boat load of spray because everything else seems like a waste of money.

Isnt the sls intake manifold better? I never mentioned porting the intake mani! I would just send the stocker to wilson and have them fab one up. So if there is not 50 crank hp to gain then there is no point in doing heads on a m156 period end of discussion. When I purchase a C63 it looks like it will get some exhaust and a boat load of spray because everything else seems like a waste of money.

Better? Depends on what you're looking for. More midrange torque maybe but you cannot use it on a M156 (won't fit under hood) and the TB placement is up front and a different ECU is used to control everything including the different cams and VCT maps.

You cannot use a sheetmetal intake on a MB engine without using standalone.

People don't understand how good the top ends of these motors are, there is 20HP or so to be gained in head porting with stock cams N/A, just goes to show that AMG did a great job similar to BMW with the S85/S65 top ends--nasty stuff.

These are stock M156 heads, they flow 390cfm/330cfm @ .500" lift @ 28" of water. We benched our own heads before and after and I've also seen one other guy in TX flow them stock and his numbers were dead on with ours 390/328cfm at the same lift.

After Hand porting we see 420-425cfm/370cfm, along with back cut stock valves and a Serdi 5 angle VJ with hand blend. We test with velocity probes not just a bench because a sewer pipe will flow 1000cfm but won't make $#@! for power. You can tell by their flow charts that they didn't gain enough airflow to justify even half the 50HP claimed gains. Facts are facts, sorry guys.

Intake Manifold:

As you can see from the intake manifold pics, you can't do anything to it, and frankly you don't need to, it's a great dual runner design--although I like the SLS TB placement better. We discovered this over 2 years ago when we purchased a complete top end and 2 sets of spare heads for our cylinder head and camshaft program. We spent over 12 months R&Ding the heads.

No disrespect to weistec but we will take the pepsi challenge with them or anyone else, and the claims of gains are just too outlandish not to comment.

These are stock M156 heads, they flow 390cfm/330cfm @ .500" lift @ 28" of water. We benched our own heads before and after and I've also seen one other guy in TX flow them stock and his numbers were dead on with ours 390/328cfm at the same lift.

After Hand porting we see 420-425cfm/370cfm, along with back cut stock valves and a Serdi 5 angle VJ with hand blend. We test with velocity probes not just a bench because a sewer pipe will flow 1000cfm but won't make $#@! for power. You can tell by their flow charts that they didn't gain enough airflow to justify even half the 50HP claimed gains. Facts are facts, sorry guys.

As you can see from the intake manifold pics, you can't do anything to it, and frankly you don't need to, it's a great dual runner design--although I like the SLS TB placement better. We discovered this over 2 years ago when we purchased a complete top end and 2 sets of spare heads for our cylinder head and camshaft program. We spent over 12 months R&Ding the heads.

No disrespect to weistec but we will take the pepsi challenge with them or anyone else, and the claims of gains are just too outlandish not to comment.

Better? Depends on what you're looking for. More midrange torque maybe but you cannot use it on a M156 (won't fit under hood) and the TB placement is up front and a different ECU is used to control everything including the different cams and VCT maps.

You cannot use a sheetmetal intake on a MB engine without using standalone.

People don't understand how good the top ends of these motors are, there is 20HP or so to be gained in head porting with stock cams N/A, just goes to show that AMG did a great job similar to BMW with the S85/S65 top ends--nasty stuff.

If there was a hood that let it fit, could you use the SLS heads?

also, how does the SLS get the extra power over the C63 ? I know my car supposedly has parts from the SLS...but is the extra power on the SLS just do to intake/heads and ecu? seems like some of the parts could be used on our engines, no? or is the whole set up just different and nothing really transfers over?